Once labeled a vulnerable incumbent, the four-term Arizona Republican is the clear front-runner against challenger J.D. Hayworth after spending some $20 million and casting his GOP opponent as a late-night infomercial huckster in a series of devastating ads. The primary is Tuesday.

McCain, who turns 74 on Aug. 29, has survived the deadly 1967 explosion on the USS Forrestal, 5 1/2 years in a Vietnam POW camp after being shot down near Hanoi and skin cancer. Politically, he has persisted through the Keating Five savings and loan scandal, and two failed bids for the White House.

"I have stood up and led the fight as a fiscal conservative and a leader on national defense and a strong supporter of the men and women who are fighting and sacrificing for this nation," McCain told a woman who questioned his record at a town-hall meeting last Thursday.

Long unpopular with some home-state conservatives, McCain immediately recognized the threat posed by Hayworth, a talk-radio host and former six-term congressman from Scottsdale. And he set out to neutralize it.

He tossed aside his self-described "maverick" label and adopted a hard-line stand on immigration just a few years after working with Democrats on a path to citizenship for those in the country illegally. "Complete the danged fence," he says in a campaign ad, three years after dismissing the effectiveness of building a fence on the U.S.-Mexico border.

A series of McCain ads called Hayworth a "huckster," showing clips of him in an infomercial telling viewers they can get free government money. It was an embarrassment for a candidate running as a fiscal conservative, and it caught Hayworth flat-footed. At first he defended it, then apologized as the story lived on for weeks.

Hayworth is undaunted. He has had an exhausting series of campaign events throughout Arizona, mostly in rural areas away from Phoenix. On a remote stretch of the U.S.-Mexico border, he criticized McCain for not supporting a change in the 14th Amendment of the Constitution to eliminate the automatic grant of citizenship to anyone born in the United States.

"In the final analysis, it ain't me, it's John McCain and his record that will be held to account," Hayworth told The Associated Press.

Hayworth aides argue that McCain is vulnerable on immigration in a state that has adopted the nation's toughest law cracking down on illegal immigrants. A Hayworth ad accused the incumbent of lying about his stand on the issue — a charge the McCain campaign denies, but which resonates with voters supporting the challenger.

"We need someone in the Senate who's going to think about Arizona. McCain just doesn't care about the constituents. He doesn't care about Arizona," said Judy Howard, a 51-year-old retired federal probation official who said she'll probably vote for Hayworth.

Hayworth has an enthusiastic crowd of supporters, but his challenge grows larger every day as the number of potential voters dwindles. In Maricopa County, where a majority of Arizonans live, more than half of 350,000 Republican early ballots had already been returned by Friday.

Jim Deakin, a contractor and Navy veteran, is pursuing the same tea party activists Hayworth is courting. Deakin's throw-the-bums-out message combined with an everyman charm and no elective office experience could siphon anti-McCain votes from Hayworth.

Despite polls showing a likely win, McCain isn't letting up. He spent $3.5 million on the race in July, most of it from the legal fund of his 2008 presidential campaign. By Aug. 4, McCain had spent $19.6 million to Hayworth's $2.6 million — a "lie and buy" strategy, Hayworth says.

But Hayworth hasn't helped his cause. He incorrectly said the United State never declared war on Nazi Germany in World War II, and suggested that a Massachusetts Supreme Court ruling on gay marriage might allow a man to marry his horse.

"I don't think J.D.'s got the analytical ability to come up with the decisions that need to be made in this environment," said Al Sondergaard, a 79-year-old retired Caterpillar manufacturing supervisor.

The winner of the GOP primary will face one of four Democrats: retired investigative journalist John Dougherty, former state administrator Cathy Eden, former Tucson City Councilman Rodney Glassman or political activist Randy Parraz. Glassman, who has loaned his campaign $500,000 and raised as much from others, is the front-runner who would face a tough time trying to beat McCain.

The cast of Survivor has nothing on Sen. John McCain.Once labeled a vulnerable incumbent, the four-term Arizona Republican is the clear front-runner against challenger J.D. Hayworth after spending some $20 million and casting his GOP opponent as a late-night infomercial...